可选orElseGet方法返回ArrayList而不是Set

问题描述 投票：1回答：3

以下代码抛出：

ClassCastException：java.util.ArrayList无法转换为java.util.Set`

Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
    .orElseGet(TreeSet::new);

findByEmailAndSistemaAndPerfil方法在Atuacao中正确返回Set中类型为Optional的两项。为什么orElseGet方法返回ArrayList？

我正在使用Spring Data Jpa。

添加：方法findByEmailAndSistemaAndPerfil定义：

public Optional<Set<Atuacao>> findByEmailAndSistemaAndPerfil(
    @Param("email") String email, @Param("idSistema") long idSistema);

已添加：

完整堆栈跟踪：

java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.util.Set
    at br.mp.mpf.autoriza.service.AtuacaoService.findAtuacoes(AtuacaoService.java:30) ~[classes/:na]
    at br.mp.mpf.autoriza.service.AtuacaoService$$FastClassBySpringCGLIB$$7bced465.invoke(<generated>) ~[classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:353) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at br.mp.mpf.autoriza.service.AtuacaoService$$EnhancerBySpringCGLIB$$961ace5.findAtuacoes(<generated>) ~[classes/:na]
    at br.mp.mpf.seguranca.SecurityConfiguration.lambda$0(SecurityConfiguration.java:123) ~[classes/:na]
    at org.springframework.security.oauth2.client.authentication.OAuth2LoginAuthenticationProvider.authenticate(OAuth2LoginAuthenticationProvider.java:120) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.authentication.ProviderManager.authenticate(ProviderManager.java:175) ~[spring-security-core-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.oauth2.client.web.OAuth2LoginAuthenticationFilter.attemptAuthentication(OAuth2LoginAuthenticationFilter.java:185) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.oauth2.client.web.OAuth2AuthorizationRequestRedirectFilter.doFilterInternal(OAuth2AuthorizationRequestRedirectFilter.java:160) ~[spring-security-oauth2-client-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_201]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]
java spring-boot java-8 spring-data-jpa optional
3个回答
1
投票

方法findByEmailAndSistemaAndPerfil可能返回Optional<ArrayLIst<Atuacao>>，因此无法以这种方式返回Set。

如果使用Java 11，则可以将Optional转换为Stream，并利用其收集器的优点：

Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
    .stream()
    .flatMap(List::stream)
    .collect(Collectors.toCollection(TreeSet::new));

如果坚持使用Java 8，则将ArrayList包裹到TreeSet中：

new TreeSet<>(
    findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
        .orElse(new ArrayList<>()));
1
投票

要么'Atuacao'必须实现Comparable，要么在创建TreeSet时需要提供一个比较器。

如SortedList中所述。

插入到排序集中的所有元素必须实现Comparable接口（或被指定的比较器接受）。此外，所有这些元素必须相互可比较：e1.compareTo（e2）（或比较器.compare（e1，e2））不得抛出ClassCastException排序集中的任何元素e1和e2。尝试违反此规定限制将导致违规方法或构造函数调用引发ClassCastException

另一个选择是如下使用哈希集。

 Set<Atuacao> a = atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)
        .orElseGet(HashSet::new);
0
投票

解决方案混合了@PattySpringDev和@ m-deinum的思想。

  1. 方法findBy现在仅返回Set；
  2. 类Atuacao现在实现了Comparable（在另一段代码中有一个比较器，已删除）；

最终代码是：

public Set<Atuacao> findByEmailAndSistemaAndPerfil(@Param("email") String email, @Param("idSistema") long idSistema);
Set<Atuacao> a = Optional.of(atuacoes.findByEmailAndSistemaAndPerfil(email.toUpperCase(),idSistema)).orElse(new TreeSet<Atuacao>());
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